Enzymatic Assay of ANCROD (EC )

Transcription

1 Enzymatic Assay of ANCROD PRINCIPLE: Fibrinogen Ancrod > Fibrin CONDITIONS: T = 37 C, ph 7.35 METHOD: Fibrometer REAGENTS: A. 143 mm 5,5-Diethylbarbiturate and 143 mm Sodium Acetate Solution (Soln A) (Prepare 275 ml in deionized water using Sodium Acetate, Trihydrate, and Barbital, Sodium Salt) B. 4.25% (w/v) Sodium Chloride Solution (Prepare 300 ml in deionized water using Sodium Chloride.) C. 36 mm 5,5-Diethylbarbiturate, 36 mm Sodium Acetate, 0.85% (w/v) Sodium Chloride Solution, ph 7.35 at 25 C (Soln B) (Prepare 1 liter by combining 250 ml of Reagent A, 200 ml of Reagent B, 217 ml of 0.1 M HCl, and 333 ml of deionized water. Adjust the ph to 7.35 at 37 C with either 1 M HCl or 1 M NaOH.) D mm Sodium Citrate Solution (Prepare 100 ml in deionized water using Citric Acid Trisodium Salt, Dihydrate.) E. 0.85% (w/v) Sodium Chloride Solution (NaCl) (Prepare 300 ml in deionized water using Reagent B.) Page 1 of 5

2 Enzymatic Assay of ANCROD REAGENTS: ) F. 7.2 mm 5,5-Diethylbarbiturate, 7.2 mm Sodium Acetate, 5.1 mm Sodium Citrate, 0.68% (w/v) Sodium Chloride, 1.0% (w/v) Bovine Serum Albumin, and 0.5% (w/v) Polyethylene Glycol (Enz Dil) (Prepare 500 ml by combining 100 ml of Reagent C, 100 ml of Reagent D, 300 ml of Reagent E, Albumin Bovine, and Polyethylene Glycol G. Plasma Solution (Plasma) (Immediately before use, reconstitute 2.0 ml of Human Plasma, lyophilized with 2 ml of deionized water. Then add 2 ml of Reagent E. Keep at room temperature.) H. Ancrod Enzyme Solution (Ancrod) (Immediately before use, reconstitute the Ancrod vial with 1 ml of deionized water. Further dilute to units/ml of Ancrod in Reagent F, in glass tubes. Serial dilutions should be made in Reagent F so that clotting times are between seconds. If the clotting time recorded is too long, increase the Ancrod concentration. If the time recorded is too short, decrease the Ancrod concentration. Subsequent dilutions are also to be made in glass tubes.) I. NIH Thrombin Standard Solution (Std) (Use Thrombin Reference Standard (Lot J) which has been diluted in Reagent F. Note: The current Standard Curve has been made with N.I.H. Thrombin Standard diluted in glass test tubes. Next Standard Curve (late 1995) will use Plastic test tubes. 1 ) PROCEDURE: Step 1: Pipette (in milliliters) the following reagents into fibrometer cups, which have been pre-warmed to 37 C. Test Reagent G (Plasma) 0.20 Allow to stand at 37 C for thirty seconds. Then add: Page 2 of 5

3 Reagent H (Ancrod) 0.10 Page 3 of 5

4 PROCEDURE: (continued) Enzymatic Assay of ANCROD Record the clotting time using a suitably thermostatted fibrometer. A 0.3 ml fibrometer probe should be used. Compare the clotting times of the Tests against a NIH Standard Curve for Thrombin clotting times versus units of Thrombin/ml. Determine the units of Ancrod of the Test from the Standard Curve. CALCULATIONS: Units/ml enzyme = (Units of Ancrod from Std Curve)(df) df = Dilution factor units/ml enzyme Units/mg solid = mg solid/ml enzyme units/ml enzyme Units/mg protein = mg protein/ml enzyme UNIT DEFINITION: Activity is expressed in NIH units obtained by direct comparison to a NIH Thrombin Reference Standard, Lot J. FINAL ASSAY CONCENTRATIONS: In a 0.30 ml reaction mix, the final concentrations are 33% (v/v) plasma, and unit ancrod (components of the enzyme diluent are not included). REFERENCE: NOTES: Human Blood Coagulation, Haemostasis, and Thrombosis (1976) p , 2nd ed., R. Biggs, ed., Blackwell Scientific Publications 1. Standards should be used immediately and kept on ice after they are dissolved. Page 4 of 5

5 NOTES: (continued) Enzymatic Assay of ANCROD 2. This assay is based on the cited reference. 3. Where our Product or Stock numbers are specified, equivalent reagents may be substituted. This procedure is for informational purposes. For a current copy of our quality control procedure contact our Technical Service Department. Page 5 of 5